JP3290709B2 - Wire-driven articulated device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire-driven articulated device.

[0002]

2. Description of the Related Art In recent years, there has been developed an industrial robot in which a hand portion or the like is constituted by a plurality of fingers having an articulated device so as to make a movement similar to a human hand. As means for independently moving the joints of such a multi-joint device, a means for driving each joint by a wire has been attracting attention because the structure can be simplified and downsized.

[0003] As this wire-driven articulated device, FIG.
And the one shown in FIG. 4 has been developed (Japanese Patent Application No. Hei.
No. 9324). This articulated apparatus is composed of a base 1 and a plurality of frames 2, 3, 4, and 5 sequentially connected to a tip of the base. That is, the first frame 2 is connected to the distal end of the base 1 by the first joint 6,
Is connected to a second frame 3 by a second joint 7 that rotates around an axis orthogonal to the first joint 6.
Similarly, the third and fourth frames 4 and 5 are connected by a third joint 8 and a fourth joint 9 which sequentially rotate around an axis parallel to the second joint 7.

[0004] The base 1 is provided with motors 10a to 10d for rotating each frame around each joint. First, as a configuration for rotating the first frame 2, as shown in FIG. 4, one end of a wire 12 wound around and fixed to a driving pulley 11 a of a motor 10 a
After being wound around the guide pulley 14 of the shaft 13 of the joint 6, the first
It is fixed to a pin 15a fixed to the frame 2, and
The other end of the wire 12 is also wound around the guide pulley 14 and fixed to the pin 15b. Therefore, the motor 10a
When the drive pulley 11a is rotated in the P direction, for example, the wire 12 is pulled, and the first frame 2 is
3 is driven to rotate in the direction of arrow Q. Also,
When the driving pulley 11a rotates in the direction opposite to the arrow P, the first frame 2 rotates in the direction opposite to the arrow Q.

As shown in FIG. 3, the wire 16 fixed around the drive pulley 11c of the motor 10c has one end on the guide roller 17 and the shaft 18 on the shaft 18, as shown in FIG. The guide roller 19 passes through the guide roller 19 and is rotated in the direction by a guide roller 20 mounted on the first frame 2.
After one turn, the roller is wound around a pulley 25 that can freely rotate on a shaft 24 of the third joint 8 via a guide roller 23 mounted on the second frame 3, and is fixed to the third frame 4. It is fixed to the provided pin 26a. Similarly, the other end of the wire 16 is also pulled through a guide roller or the like through a pulley 25.
After being wound around, the pin 26 fixed to the third frame 4
b. Therefore, when the motor 10c is driven, the wire 16 is pulled and the third frame 4
Are turned up and down in FIG. 3 around the axis 24 of the third joint 8.

As described above, in the articulated apparatus, a plurality of wires fixed to each frame are sequentially extended in the plurality of frames, and tension is applied to each of these wires independently, so that each frame is It is configured to be driven to rotate independently.

[0007]

By the way, a wire guide mechanism for guiding a wire of this articulated apparatus has a structure in which an arbitrary frame rotates around a joint on a supporting side thereof.
The interference type in which the frame on the tip side of this frame rotates, and the interference amount in which the frame on the tip side from this frame turns when the frame on the support side turns (that is, the rotation amount)
There is a non-interference type in which is reduced.

FIG. 5 shows an example of an interference-type wire guide mechanism. In this mechanism, a frame 31 is connected to a support side of an arbitrary frame 30 by a support side joint 32, and a frame 33 is connected to a distal side of the frame 30 by a distal side joint 34. This frame 30
Wire 3 for rotating and driving more distal end frame 33
5 extend along each frame, and the supporting joint 3
It is wound around two guide pulleys 36 and further guided by a pair of guide pulleys 37. In the interference type, the rotation center (O) of the support side joint 32 is provided coaxially with the rotation center of the guide pulley 36. The points at which the wire 35 is supported by the guide pulleys 36 and 37 are referred to as point T and point P, respectively.

[0009] Here, as the center an arbitrary frame 30 is a rotation center (O), when to be turned from the point P to P ₁ point, the distance between the support points PT is after rotation P ₁ T ₁
Equal to the distance between As a result, by the amount of distance the arc TT _1, will be the wire 35 is pulled, the frame 33 that is rotationally driven by a wire 35 is to be rotated.

In such an interference type wire guide mechanism, the leading end frame 3 is in proportion to the diameter of the guide pulley 36.
3 (that is, the amount of rotation of the frame 33) is large, and when controlling this interference-type wire guide mechanism, it is necessary to perform an operation to guarantee the amount of interference with other joints.

For these reasons, the above-mentioned non-interference type wire guide mechanism has been proposed. In this mechanism, a pair of guide pins is provided with a gap as large as the diameter of the wire so that the wire passes over the center of rotation (O) of the supporting joint of an arbitrary frame. Has been inserted. Further, instead of a pair of guide pins, an elongated hole for guiding a wire may be provided.

However, in such a non-interference type wire guide mechanism, the pin may be bent due to the tension of the wire, and the wire may be frequently replaced due to severe pain of the wire due to friction. There is a problem that the life of the device is short.

An object of the present invention is to solve the above-mentioned problems, and to extend the life of the wire and the life of the device itself, and at the same time, to rotate any frame around the joint on its supporting side. It is an object of the present invention to provide a non-interfering wire-driven multi-joint device in which the amount of interference (that is, the amount of rotation) at which the frame on the distal end side of the frame rotates even when it moves is reduced.

[0014]

According to the present invention, a plurality of frames sequentially connected by a joint, a wire extending through the plurality of frames so as to sequentially pass through the joint, and at least one of the frames are provided. And a pair of guide pulleys having the same radius for holding and supporting the wire, and wherein the frame is rotated through the joint by pulling the wire, wherein the joint and the pair of guides are provided. The guide pulley is arranged so that the rotation center of the joint and the rotation center of the pair of guide pulleys are deviated, and the rotation center of the pair of guide pulleys is fixed to the frame, and the pair of guide pulleys Pulley radius,
A ratio between the rotational center of the pair of guide pulleys and the amount of deviation of the rotational center of the pair of guide pulleys from the rotational center of the joint is 0.15 to 0.4.

[0015]

According to the present invention, the rotation centers of the pair of guide pulleys are fixed to the frame, the radius of the pair of guide pulleys and the deviation of the rotation center of the pair of guide pulleys from the rotation center of the joint. The ratio to the position is 0.15-0.
By setting 4, it is possible to suppress a change in the length of the wire even when the frame rotates.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a wire-driven articulated apparatus according to an embodiment of the present invention.

FIG. 1 is a schematic diagram of a wire guide mechanism of a wire-driven articulated apparatus according to one embodiment of the present invention. In this FIG. 1, similarly to the guide mechanism shown in FIG. 5, a frame 31 is connected to a support side of an arbitrary frame 30 by a support joint 32, and a frame 33 is connected to a distal end side of the frame 30 by a distal joint 34. ing. This frame 30
Wire 3 for rotating and driving more distal end frame 33
5 extend along each frame, and the frame 30
Is provided with a pair of guide pulleys 37 for guiding the wire 35.

In the present embodiment, a pair of guide pulleys 40, 40 for guiding the wire 35 are displaced as described later. That is, the frame 33 on the tip side
The wire 35 for rotating and driving the arbitrary frame 3
0 of the supporting side joint 32 can pass through the center of rotation (O).
5 is disposed so that the contact point 5 contacts the support point (R) on the outer periphery of the guide pulley 40. That is, the rotation center (Q) of the guide pulley 40 is shifted by a radius (r) in a direction orthogonal to a line connecting the support point (R) and the rotation center (O) of the support side joint 32. Have been.

Further, the rotation center (Q) of the guide pulley 40 is shifted downward in FIG. 1 from the rotation center (O) of the supporting joint 32 (the supporting point (R) and the rotation center (O) of the supporting joint 32). (In the direction of the line segment connecting the two), the guide pulley 40 is deviated within the radius (r). Here, it is assumed that the diameter of the wire 35 is sufficiently smaller than the radius of the guide pulley 40. However, if the diameter of the wire 35 is too large to be neglected, r is the radius of the wire 35 and the guide diameter. It may be considered as the sum of the radii of the pulley 40.

As described above, since the rotation center (O) of the support joint 32 and the rotation center (Q) of the guide pulley 40 are not aligned with each other and are displaced, the frame 30 is rotated at the center of rotation. (O) when rotated from the point P as a center to the P ₁ point, and the wire 35 passes through the arc RS and a line segment P ₁ S on the guide pulley 40. In this case, an ideal length of the wire 35 serving as a non-interference type is path ROP _1. Therefore, the smaller the difference between the route RSP ₁ and the route ROP ₁ is, the less interference type the distal end frame 33 is hardly rotated even when the frame 30 is rotated.

[0021] Therefore, difference in path RSP ₁ and path ROP ₁ sets the χ-у coordinate axes and deduction 0, coordinates (χ _1, у ₁₎ of P ₁ point coordinates of the point Q (X ₂ , y)

[0022]

(Equation 1) here,

[0023]

(Equation 2)

[0024]

(Equation 3) Can be obtained as

Here, the ratio p of the diameter (r) of the guide pulley 40 and the amount of deviation OR in which the rotation center (Q, Q1) is deviated from the rotation center (O) is used as a variable, and the path is obtained from the equation (1). RSP
The difference Δd between ₁ and the route ROP ₁ is obtained. The result is shown in FIG. FIG. 2 shows that in equation (1), r = 2.5 mm, q
= 1 (rotation by 45 degrees) and k = 0.625, showing the relationship between the ratio p and the path difference △ d. As is clear from this figure, the path difference △ near the ratio p = 0.28.
d is zero, which is a non-interference type wire guide mechanism in which the distal end frame 33 does not rotate even when the frame 30 rotates. Therefore, when the ratio p is 0.15 to 0.4, even if the frame 30 rotates, the leading end frame 3
It is considered that 3 hardly rotates.

On the other hand, when the path difference in the interference-type wire guide mechanism shown in FIG. 5 is obtained, r = 2.5 mm, and when the frame 30 is rotated 45 degrees around the rotation center (O), Path difference (ie, length of interfering wire)
Is 1.96 mm. Therefore, it is clear that the effect of the present invention is remarkable.

The present invention is not limited to the above-described embodiment, but can be variously modified.

[0028]

As described above, according to the present invention, a change in the length of the wire can be suppressed even when the frame rotates. For this reason, the tension applied to the wire can be reduced, and the rotation of the frame on the distal end side from the rotating frame can be reduced. Further, as described above, the change in the length of the wire can be reliably suppressed in practical use with a very simple structure.

[Brief description of the drawings]

FIG. 1 is a schematic view of a wire guide mechanism of a wire-driven articulated device according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a ratio p and a path difference Δd.

FIG. 3 is a cross-sectional side view of a conventional wire-driven articulated device.

FIG. 4 is another side view of the wire-driven articulated device shown in FIG. 3;

FIG. 5 is a schematic diagram of a wire guide mechanism of the interference-type wire-driven articulated device.

[Explanation of symbols]

 30 Arbitrary frame 32 Joint on supporting side 33 Frame on tip side 40 Guide pulley

Claims (2)

(57) [Claims] A plurality of frames sequentially connected by joints; a wire extending through the plurality of frames so as to sequentially pass through the joints; and a wire provided on at least one of the frames and holding the wires therebetween. A pair of guide pulleys having the same radius to support, and a wire-driven multi-joint device in which a frame is rotated via a joint by pulling a wire, wherein the joint and the pair of guide pulleys are A rotation center and a rotation center of the pair of guide pulleys are arranged so as to be deviated, and a rotation center of the pair of guide pulleys is fixed to the frame. The ratio of the deviation of the rotation center of the pair of guide pulleys from the rotation center to the deviation amount is 0.15 to 0.15.
0.4. 2. The wire-driven multi-joint apparatus according to claim 1, wherein the center of rotation of the pair of guide pulleys is deviated toward the support side with respect to the center of rotation of the joint.